1. Field of Invention
The present invention relates to a monopole antenna, more particularly, to a symmetric-slot monopole antenna.
2. Related Art
With the development of wireless communication, miniaturization is the trend of the design of electronic devices. In order to comply with the trend, the size of antenna needs to decrease. At present, the widely used small-sized antenna include planar antenna and chip antenna. There are many types of planar antenna, such as micro-strip antenna, printed antenna, and planar inverted-F antenna (PIFA). In general, printed dipole antenna are commonly used in wireless communication devices. In terms of its design, a dipole antenna has a radiation part that extends to the two ends of the antenna and therefore is of a long antenna structure. Thus, the miniaturization of electronic devices for wireless communication are hard to realize. Further, the manufacture of printed antenna is complicated and is costly.
In order to increase the speed of wireless transmission, MIMO (multiple-input multiple-output) antennas have become increasingly popular. An MIMO antenna uses a plurality of independent antennas which are connected separately to different signal processing circuits. As an example, for an MIMO antenna with three independent antennas, two of the independent antennas are used to transmit signals and the other one is used to receive signals. By assigning different functions to different independent antennas, the speed of signal-transmission is increased. Under this situation, if the above-described printed antenna structure was adopted, the overall size of the antenna would be even larger, and the current demand for miniaturization of electronic devices could not be met.
Therefore, how to provide a low-cost and easy-to-produce antenna has become an important topic of research.